Recently, the making of inertial sensing part by the use of micro-electromechanical system (MEMS) has come into being as the size of those thus fabricated inertial sensing parts are greatly minimized. Therefore, it is popular to design and apply inertial sensing parts for human movement detection. Generally, accelerometers are used for detecting human movements of linear path while gyroscopes are used for detecting human movements of arc path.
For instance, as disclosed in U.S. Pat. No. 6,183,365, a single-axis accelerometer worn on the wrist of a user is used for detecting accelerations of a straight punch while measuring the maximum and minimum of the detected acceleration during the punching action for computing an impact power generated by the straight punch. However, the movement measuring device disclosed in U.S. Pat. No. 6,183,365 can only detect a specific human movement of linear path as a straight punch, which will require an additional gyroscope for detecting angular velocities while the specific human movement follows an arc path, i.e. as the punching action is a hook.
Therefore, in an inertial movement measuring device for sensing the movement of the human body, accelerometers are used for detecting when the specific human movements follows linear paths while gyroscopes are used for detecting when the specific human movements follows an arc path or rotation. Since the technique of making an accelerometer and that of a gyroscope are too different, there is no method available for making accelerometer and gyroscope in an integrated manufacturing process. Therefore, it is require to have accelerometers and gyroscopes independent thereto to be applied and enabled at the same time for sensing a human movement along linear/arc path. Nevertheless, from the signal processing point of view, the variety of signals coming from the accelerometers and gyroscopes at the same time will complicate the computation for measuring the human movement, and from the manufacturing cost of view, the making of an apparatus integrating accelerometers and gyroscopes is going to be expensive. Although there are many prior-art methods applying inertial measuring device for detecting human body motions, none of them had addressed the aforesaid problems.
Therefore, there is need for a sensing device, being adapted to adhere to a human body, which is capable of determining and measuring linear and arc movements of the body at the same time by a two-axis accelerometer without the help of other inertial sensing devices like gyroscope.